Re: Does this suggestion APPLY TO THE INTERNET AS A WHOLE?
SDN requires low level protocols working end-to-end, at the lowest level these are near enough cast in stone because everything has to work together. All the routing protocols were created when bandwidth1, cpu & memory availability was low, expensive and mostly using dedicated circuits to allow QOS & security.
Now that streaming multiple hi-def video feeds using inline encryption on public circuits doesn't squeeze hardware capabilities SDN2 can easily build flexible networks on the fly by automating VPN and routing protocol connections without worrying too much about bringing anything down.
From a security standpoint, there are fewer points of entry for any network offset by the far worse level of compromise achieved should one be breached. Good CIOs these days should be expecting a breach and looking to achieve the shortest elapsed time possible from problem isolation to fix.
1 leased line with just POTS dialup, 2B1D-ISDN very nice, full T1/E1 utter luxury!
2Single vendor unless you really want to learn how many assumptions are being made by different systems (give it a decade or so).